Have you tried actually finding a fast lens in E Mount though? Sony always has a lot of show for limited gusto with the majority of their lenses being above F/4

Sony is incapable of completing a project before losing interest and moving on to the next. The E mount has been pretty much abandoned. Until the next sparkly thing catches Sony's eye (which will create yet another kludge for your mount of choice), you are expected to use FE lenses instead.